Nickel-iron Dithiolato Hydrides Relevant to the [NiFe]-hydrogenase Active Site

J Am Chem Soc. 2009 May 27;131(20):6942-3. doi: 10.1021/ja902570u.

Abstract

The ferrous dithiolato carbonyl Fe(S(2)C(3)H(6))(CO)(2)(dppe) (1) condenses with NiCl(2)(dppe) to give [FeNi(pdt)(mu-Cl)(CO)(dppe)(2)]BF(4) ([2Cl](+)). The corresponding reaction of the ditosylate Ni(OTs)(2)(dppe) gave the dication [(CO)(2)(dppe)Fe(pdt)Ni(dppe)](OTs)(2) ([2(CO)](OTs)(2)) (pdt = 1,3-propanedithiolate; dppe = 1,2-C(2)H(4)(PPh(2))(2); OTs(-) = CH(3)C(6)H(4)-4-SO(3)(-)). Reduction of the bimetallic dicarbonyl with borohydride salts afforded impure, thermally stable hydride, [(CO)(dppe)Fe(pdt)(mu-H)Ni(dppe)](+) ([2H](+)). A reliable route to NiFe(SR)(2)H species entailed protonation of (CO)(3)Fe(pdt)Ni(dppe) to give [(CO)(3)Fe(pdt)(mu-H)Ni(dppe)](+) ([3H](+)). The iron-nickel dithiolato hydride, [3H]BF(4), was characterized crystallographically: as anticipated by biophysical studies, the hydride ligand is bridging, the Fe center is octahedral, and the Ni center is pentacoordinate. Solutions of [3H]BF(4) undergo substitution by dppe to give [2H](+). The hydride undergoes rapid deprotonation and is an electrocatalyst for hydrogen evolution from trifluoroacetic acid. Oxidation of 3 gives a mixed valence species [3](+), a potential model for the Ni-L state.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Catalytic Domain
  • Hydrogenase / chemistry*
  • Hydrogenase / metabolism
  • Iron Compounds / chemical synthesis
  • Iron Compounds / chemistry*
  • Models, Molecular
  • Nickel / chemistry*
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry*
  • Organophosphorus Compounds / chemistry*
  • Sulfhydryl Compounds / chemical synthesis
  • Sulfhydryl Compounds / chemistry*

Substances

  • Iron Compounds
  • Organometallic Compounds
  • Organophosphorus Compounds
  • Sulfhydryl Compounds
  • bis(diphenylphosphine)ethane
  • Nickel
  • nickel-iron hydrogenase
  • Hydrogenase